---
name: "Cache::Ref::CLOCK"
section: "3pm"
platform: "linux"
package: "libcache-ref-perl"
version: "0.04-1.1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Cache::Ref::CLOCK"
---

# Cache::Ref::CLOCK(3pm)

CLOCK cache replacement algorithm

## NAME

Cache::Ref::CLOCK - CLOCK cache replacement algorithm

## SYNOPSIS

```
    my $c = Cache::Ref::CLOCK->new(
        size => $n,
        k    => $k,
    );
```

## DESCRIPTION

This algorithm is provides a second chance FIFO cache expiry policy using a circular buffer.

It is a very well accepted page replacement algorithm, but largely for reasons which are irrelevant in this context (cache hits don't need to be serialized in a multiprocessing context as they only require an idempotent operation (setting a bit to 1)).

## ATTRIBUTES

- size

  The size of the live entries.

- k

  This is the initial value given to all hit entries.

  As the hand moves through the circular buffer it decrements the counters.

  The default is `1`, providing semantics similar to a second chance FIFO cache.

  Larger values of `"k"` model LRU more accurately.

  This is pretty silly though, as Cache::Ref::LRU is probably way more efficient for any `"k"` bigger than 1.

## AUTHOR

Yuval Kogman

## COPYRIGHT AND LICENSE

This software is copyright (c) 2010 by Yuval Kogman.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.